Bottom firing detonator



Dec. 18, 1356 J. L. WORZEL 2,774,304

BOTTOM FIRING DETONATOR Filed March 12, 1953 4a Fq'g 1 4 7 f5 4 5a 48 j 5/ x. i i. a

BOTTOM FIRING DETONATOR John L. Worzel, Palisades, N. Y., assignor to the United States of America as represented by the Secretary of the Navy Application March 12, 1953, Serial No. 341,867

1 Claim. (Cl. 102-7) This invention relates to a device for detonating an explosive charge. More particularly the invention is concerned with a detonator which is set off by pressure of a fluid medium in which the detonator may be desired to be employed, as for example the deep ocean.

In deep water seismic measurements it is often desirable to operate a recording mechanism for a long period of time and to proceed away from the recorder firing charges at the ocean bottom. In order to do this it is necessary to have a detonator which will initiate an explosion precisely at the time at which the explosive charge hits against the ocean bottom.

An object of the invention therefore is to deal with this problem and to devise a detonator'which provides for positive initiation of an explosion by reason of contact of an explosive charge with the ocean bottom. It is an object of the invention to combine with such a device means for insuring adequate safetyprovisions.

I have found that an excellent way of performing this function is to employ hydrostatic pressure efiects occurring below the surface of the ocean to collapse a rigid closed container. An important aspect of the invention, therefore, is a pressure-sensitive collapsible closed container carrying a percussive material with which is combined a triggering arrangement responsive to contact with the ocean bottom.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a view in elevation and partial cross section;

Fig. 2 is another elevation and partial cross section taken on a line at right angles to that of Fig. 1; and

Fig. 3 is a detail cross-sectional View. 7

v The structure shown in the drawings in general includes the combination of a pressure-sensitive collapsible detonator and means operated by contact with the ocean bottom for suddenly exposing the detonator to hydrostatic pressure.

Considering the specific structure noted in greater detail, 10 denotes a detonator of a type which is subject to being collapsed at some predetermined hydrostatic pres sure. The novel features of this detonator element have been described and claimed in the co-pending application of William M. Ewing and John L. Worzel entitled, Method and Apparatus for Detonating Explosive Charge, Serial No. 341,952, filed March 12, 1953. However, a brief description of the construction and operation of the detonatorelement is given here in order to point out more clearly the construction and features which form thenovel subject matter of the present invention.

The detonator 10 is made up of a closed cylindrical metal case of relatively short length such as three to four inches and an overall diameter for instance of threeeighths of an inch. The gauge and type of metal used are so chosen as to determine the depth at which hydro- States Patent means consisting of two strips of repeating paper caps 16 and 18. These strips 16' and 18 are in spaced relation to the walls of the detonator tube 10. The tube is closed at either end by covers 20 and 22, and suitable sealing means such as a waterproof resin may be utilized to tightly seal these covers. In use this device is lowered to a depth at which hydrostatic pressure suddenly collapses the side walls of the detonator occurring adjacent to the paper caps 16 and 18. As the walls collapse, they strike against these caps, exploding them, and thus starting a progressive cycle of firing through the blasting cap 14 and the pentolite 12 to initiate an explosion of a main charge of explosive such as TNT. The arrangement of the detonator in a cast body 24 of TNT is further illustrated in Figs. 1 and 2, in which there is also indicated a booster charge 26 of high explosive such as tetryl surrounding the lower end of the detonator 10. Various other arrangements involving a train of progressively firing explosives may be employed.

In accordance with the present invention, I provide a container 28 for the main body of explosive, which may be of cardboard for example, having a cover member 30,

through which is inserted the detonator 10 in the manner indicated in the drawings. The numeral 31 denotes a bracket secured to the cover. Surrounding the detonator at the outer side of the cover 30 is a collar 32 on which is mounted a rigid closed tubular element 34, arranged in spaced relation to the detonator 10 as shown in Fig. 3. The tubular element may conveniently be comprised of a heavy glass envelope for example, and may be secured in place by means of a resilient sleeve member 36. The upper end of the glass envelope or tubular element is supported in a framework extending out from the bracket 31. The framework consists of a ring 38 carrying arms 40 which support a cap 42 curved to fit over the closed extremity of the tubular element.

An essential characteristic of the glass envelope, in addition to those noted, is that it shall be of an inherently brittle nature such that while it is capable of resisting a relatively large hydrostatic pressure, it nevertheless may be readily shattered by a sharp blow. A suitable thickness of glass meets these requirements.

Means for delivering a sharp blow against the glass en velope is provided at the top of the bracket 31. This mechanism consists of a mousetrap arrangement including a curved striking arm 44, which may be maintained under tension by a spring 46 when held in a position such trated by the cylindrical block 52. The bulky end portion of the trigger is designed to afiord a relativelylarge contact area for hitting against the ocean bottom'and releasing the striking arm.

' As viewed in Fig. 1, movement of the ring portion 51 and the cylindrical block 52 in clockwise direction about the yoke 53 will trip the tongue 48 and allow the striking arm to hit against the glass envelope 34. Such an action shatters the glass envelope and thus suddenly exposes the detonator 18 to hydrostatic pressure, which in turn colable type of stop means consists in a replaceable element 55' which may, for example, be very readily soluble in water. This element is inserted between the cylinder block 52 and the bracket 51 in the position indicated in Fig. 1 of the drawings. By this arrangement, the trigger is jammed and movement is prevented until the device has been immersed in water and the stop element 55 has dissolved away. It should be observed that dissolving the stop element does nottrip the trigger but merely leaves it in a position such that it'niay be tripped upon contact with the ocean bottom.

As viewed'in the drawings, the detonator assembly ap- 'pears at the top of the sheet. This arrangement has been It will be seen from the above description that have provided a positive, safe and eificient bottom-firing detonator. The glass envelope may be readily made strong enough to withstand the hydrostatic pressure encountered at considerable ocean depths and yet may be readily broken by the triggering arrangement described. In actual practice the device has proven to be a dependable means of carrying out precise firing of heavy charges at considerable ocean depths. It is also pointed out that the collapsible type of detonator, in combination with the triggering means, avoids the need for holding lines to. control and set oif a charge in a conventional manner. Special precautions to keep the main charge dry are also obviated. This is due to the fact that the small detonator is a sealed unit and necessarily stays dry until it is collapsed by hydrostatic pressure. Since the main charge can be fired in this way, no waterproofing container requirements for the-main charge are necessary, and a simple, cheap container of cardboard or other light material may be employed with the charge being set ofi in a wet condition.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings.

ticed otherwise than as specifically described.

What is claimed. is:

In combination with a casing containing an explosive, a bomb arming mechanism comprising, an elongated hollow element in said casing, said elongated element having a portion protrudingthrough said-casing, percussive material within said hollow element, said element being adapted to collapse suddenly upon exposure to pressure exceeding pr e in ntens y a f an i l n lop 611.6108? ing said protrudingportion and isolating said portion from v ambient pressures, a pivoted arm mounted in a position to strike said frangible envelope, resilient means exerting a force upon said arm, latch means for preventing said arm from striking said envelope, and inertial means for unlatching said arm.

References Cited in the file of this patent UNITED- STATES PATENTS It is therefore to be understood that within the. scope of the appendedclaim the invention may be prac- Germany n 4, 1904 

